/** @file
 *
 * Dynamic memory manager
 *
 */

/*
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * This file is part of the lwIP TCP/IP stack.
 *
 * Author: Adam Dunkels <adam@sics.se>
 *
 */





#include <string.h>
#include "lwip/arch.h"
#include "lwip/opt.h"
#include "lwip/def.h"
#include "lwip/mem.h"

#include "lwip/sys.h"

#include "lwip/stats.h"


#if 0  // we use standard malloc()/realloc()/free() functions

struct mem
{
        mem_size_t next, prev;
#if MEM_ALIGNMENT == 1
        u8_t used;
#elif MEM_ALIGNMENT == 2
        u16_t used;
#elif MEM_ALIGNMENT == 4
        u32_t used;
#elif MEM_ALIGNMENT == 8
        u64_t used;
#else
#error "unhandled MEM_ALIGNMENT size"
#endif /* MEM_ALIGNMENT */
};

static sys_sem_t mem_sem;

static struct mem *ram_end;
static u8_t ram[MEM_SIZE + sizeof(struct mem) + MEM_ALIGNMENT];

#define MIN_SIZE 12
#if 0 /* this one does not align correctly for some, resulting in crashes */
#define SIZEOF_STRUCT_MEM (unsigned int)MEM_ALIGN_SIZE(sizeof(struct mem))
#else
#define SIZEOF_STRUCT_MEM (sizeof(struct mem) + \
                          (((sizeof(struct mem) % MEM_ALIGNMENT) == 0)? 0 : \
                          (4 - (sizeof(struct mem) % MEM_ALIGNMENT))))
#endif

static struct mem *lfree;   /* pointer to the lowest free block */



static void
plug_holes(struct mem *mem)
{
        struct mem *nmem;
        struct mem *pmem;

        LWIP_ASSERT("plug_holes: mem >= ram", (u8_t *)mem >= ram);
        LWIP_ASSERT("plug_holes: mem < ram_end", (u8_t *)mem < (u8_t *)ram_end);
        LWIP_ASSERT("plug_holes: mem->used == 0", mem->used == 0);

        /* plug hole forward */
        LWIP_ASSERT("plug_holes: mem->next <= MEM_SIZE", mem->next <= MEM_SIZE);

        nmem = (struct mem *)&ram[mem->next];
        if (mem != nmem && nmem->used == 0 && (u8_t *)nmem != (u8_t *)ram_end)
        {
                if (lfree == nmem) {
                        lfree = mem;
                }
                mem->next = nmem->next;
                ((struct mem *)&ram[nmem->next])->prev = (u8_t *)mem - ram;
        }

        /* plug hole backward */
        pmem = (struct mem *)&ram[mem->prev];
        if (pmem != mem && pmem->used == 0)
        {
                if (lfree == mem) {
                        lfree = pmem;
                }
                pmem->next = mem->next;
                ((struct mem *)&ram[mem->next])->prev = (u8_t *)pmem - ram;
        }

}
void
mem_init(void)
{
        struct mem *mem;

        memset(ram, 0, MEM_SIZE);
        mem = (struct mem *)ram;
        mem->next = MEM_SIZE;
        mem->prev = 0;
        mem->used = 0;
        ram_end = (struct mem *)&ram[MEM_SIZE];
        ram_end->used = 1;
        ram_end->next = MEM_SIZE;
        ram_end->prev = MEM_SIZE;

        mem_sem = sys_sem_new(1);

        lfree = (struct mem *)ram;

#if MEM_STATS
        lwip_stats.mem.avail = MEM_SIZE;
#endif /* MEM_STATS */
}
void
mem_free(void *rmem)
{
        struct mem *mem;

        if (rmem == NULL) {
                LWIP_DEBUGF(MEM_DEBUG | DBG_TRACE | 2, ("mem_free(p == NULL) was called.\n"));
                return;
        }

        sys_sem_wait(mem_sem);

        LWIP_ASSERT("mem_free: legal memory", (u8_t *)rmem >= (u8_t *)ram &&
                    (u8_t *)rmem < (u8_t *)ram_end);

        if ((u8_t *)rmem < (u8_t *)ram || (u8_t *)rmem >= (u8_t *)ram_end) {
                LWIP_DEBUGF(MEM_DEBUG | 3, ("mem_free: illegal memory\n"));
#if MEM_STATS
                ++lwip_stats.mem.err;
#endif /* MEM_STATS */
                sys_sem_signal(mem_sem);
                return;
        }
        mem = (struct mem *)((u8_t *)rmem - SIZEOF_STRUCT_MEM);

        LWIP_ASSERT("mem_free: mem->used", mem->used);

        mem->used = 0;

        if (mem < lfree) {
                lfree = mem;
        }

#if MEM_STATS
        lwip_stats.mem.used -= mem->next - ((u8_t *)mem - ram);

#endif /* MEM_STATS */
        plug_holes(mem);
        sys_sem_signal(mem_sem);
}
void *
mem_reallocm(void *rmem, mem_size_t newsize)
{
        void *nmem;
        nmem = mem_malloc(newsize);
        if (nmem == NULL) {
                return mem_realloc(rmem, newsize);
        }
        memcpy(nmem, rmem, newsize);
        mem_free(rmem);
        return nmem;
}

void *
mem_realloc(void *rmem, mem_size_t newsize)
{
        mem_size_t size;
        mem_size_t ptr, ptr2;
        struct mem *mem, *mem2;

        /* Expand the size of the allocated memory region so that we can
           adjust for alignment. */
        if ((newsize % MEM_ALIGNMENT) != 0) {
                newsize += MEM_ALIGNMENT - ((newsize + SIZEOF_STRUCT_MEM) % MEM_ALIGNMENT);
        }

        if (newsize > MEM_SIZE) {
                return NULL;
        }

        sys_sem_wait(mem_sem);

        LWIP_ASSERT("mem_realloc: legal memory", (u8_t *)rmem >= (u8_t *)ram &&
                    (u8_t *)rmem < (u8_t *)ram_end);

        if ((u8_t *)rmem < (u8_t *)ram || (u8_t *)rmem >= (u8_t *)ram_end) {
                LWIP_DEBUGF(MEM_DEBUG | 3, ("mem_realloc: illegal memory\n"));
                return rmem;
        }
        mem = (struct mem *)((u8_t *)rmem - SIZEOF_STRUCT_MEM);

        ptr = (u8_t *)mem - ram;

        size = mem->next - ptr - SIZEOF_STRUCT_MEM;
#if MEM_STATS
        lwip_stats.mem.used -= (size - newsize);
#endif /* MEM_STATS */

        if (newsize + SIZEOF_STRUCT_MEM + MIN_SIZE < size) {
                ptr2 = ptr + SIZEOF_STRUCT_MEM + newsize;
                mem2 = (struct mem *)&ram[ptr2];
                mem2->used = 0;
                mem2->next = mem->next;
                mem2->prev = ptr;
                mem->next = ptr2;
                if (mem2->next != MEM_SIZE) {
                        ((struct mem *)&ram[mem2->next])->prev = ptr2;
                }

                plug_holes(mem2);
        }
        sys_sem_signal(mem_sem);
        return rmem;
}
void *
mem_malloc(mem_size_t size)
{
        mem_size_t ptr, ptr2;
        struct mem *mem, *mem2;

        if (size == 0) {
                return NULL;
        }

        /* Expand the size of the allocated memory region so that we can
           adjust for alignment. */
        if ((size % MEM_ALIGNMENT) != 0) {
                size += MEM_ALIGNMENT - ((size + SIZEOF_STRUCT_MEM) % MEM_ALIGNMENT);
        }

        if (size > MEM_SIZE) {
                return NULL;
        }

        sys_sem_wait(mem_sem);

        for (ptr = (u8_t *)lfree - ram; ptr < MEM_SIZE; ptr = ((struct mem *)&ram[ptr])->next) {
                mem = (struct mem *)&ram[ptr];
                if (!mem->used &&
                                mem->next - (ptr + SIZEOF_STRUCT_MEM) >= size + SIZEOF_STRUCT_MEM)
                {
                        ptr2 = ptr + SIZEOF_STRUCT_MEM + size;
                        mem2 = (struct mem *)&ram[ptr2];

                        mem2->prev = ptr;
                        mem2->next = mem->next;
                        mem->next = ptr2;
                        if (mem2->next != MEM_SIZE) {
                                ((struct mem *)&ram[mem2->next])->prev = ptr2;
                        }

                        mem2->used = 0;
                        mem->used = 1;
#if MEM_STATS
                        lwip_stats.mem.used += (size + SIZEOF_STRUCT_MEM);
                        /*      if (lwip_stats.mem.max < lwip_stats.mem.used) {
                          lwip_stats.mem.max = lwip_stats.mem.used;
                        } */
                        if (lwip_stats.mem.max < ptr2) {
                                lwip_stats.mem.max = ptr2;
                        }
#endif /* MEM_STATS */

                        if (mem == lfree) {
                                /* Find next free block after mem */
                                while (lfree->used && lfree != ram_end) {
                                        lfree = (struct mem *)&ram[lfree->next];
                                }
                                LWIP_ASSERT("mem_malloc: !lfree->used", !lfree->used);
                        }
                        sys_sem_signal(mem_sem);
                        LWIP_ASSERT("mem_malloc: allocated memory not above ram_end.",
                                    (mem_ptr_t)mem + SIZEOF_STRUCT_MEM + size <= (mem_ptr_t)ram_end);
                        LWIP_ASSERT("mem_malloc: allocated memory properly aligned.",
                                    (unsigned long)((u8_t *)mem + SIZEOF_STRUCT_MEM) % MEM_ALIGNMENT == 0);
                        return (u8_t *)mem + SIZEOF_STRUCT_MEM;
                }
        }
        LWIP_DEBUGF(MEM_DEBUG | 2, ("mem_malloc: could not allocate %"S16_F" bytes\n", (s16_t)size));
#if MEM_STATS
        ++lwip_stats.mem.err;
#endif /* MEM_STATS */
        sys_sem_signal(mem_sem);
        return NULL;
}



#endif